Is voice chat on by default in the Alpha?

If I speak into a microphone without pressing any kind of push-to-talk button, will my voice be broadcast into the game? You see, I have a microphone built into my laptop and while playing some of the game today I got a little bit frustrated at a couple players. I never type bad things about other players, neither do I use voice chat, but I do sometimes get carried away when I think I am talking to myself. At this point, I’m really worried that some of the things I said might have actually been broadcast into the game when I did not intend to do so. The audio section of the options menu appears to not be finished, so I can’t check myself. Is it possible that this may have happened? Thank you.